Analysis of Tree Bark Shows Global Spread of Insecticides

Published: October 10, 1995

WASHINGTON, Oct. 9—
An analysis of tree bark suggests that insecticides and fungicides have spread over the globe, often thousands of miles from where they were used, and that some chemicals sprayed decades ago are still affecting the environment.

Bark from 90 sites around the world bears traces of chemicals related to DDT, chlordane and aldrin and to 19 other pesticides or fungicides, said Ronald A. Hites, a chemistry professor at Indiana University.

He said that the survey showed that some of the chemicals evaporated in hotter climates and were carried to cooler areas, where they condensed out of the atmosphere. For this reason, he said, bark from near the Arctic Circle carried traces of insecticides that probably were sprayed in tropical areas.

A report on the study by Dr. Hites and a colleague, Staci L. Simonich, was published in the Sept. 29 issue of the journal Science.

Dr. Hites said even though DDT has been banned for decades in most industrial countries, decayed byproducts are still around and easily detected in the bark. Another commonly detected insecticide was endosulfan, which is used in rice cultivation.